Good Deal on Drill Bits!

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KJ Ryu
Posts: 990
Joined: Sun Jun 10, 2012 8:03 am
Location: Casper

Re: Good Deal on Drill Bits!

Post by KJ Ryu » Tue Dec 17, 2019 1:38 am

itselliott wrote:
Sat Dec 14, 2019 2:55 pm
I wish I could hold a class on sharpening drills...………..As a tool & Die apprentice , years ago, I had 2 old German toolmakers drive me to tears "educating" me in the drill sharpening process...………..It is really super easy to sharpen a drill once you have got the process down.....
Agreed. As a machinist doing oilfield equipment repair (valve and BOP bodies), this is indispensable:

Image

118deg for standard metals, 135 for hard stuff, like Inconel.
Ron

2005 KJ, Hit-n-Run, 2am 6-17-2012, Totaled. :mad:
1977 SJ J10, 4v360, T18, D20, 37x14s, SOA & SF on tons, still ugly.
1978 SJ Wagoneer, 4v360, QT, 33x12.5s, lift by Sawzall :-bd NOT Running :(
1977 SJ J10, SniperEFI 401, QT, D44s, 31X10.5s :fsj:
2006 KJ
Mars wrote:One man's trans leak is another's penetrating oil :D


KJ Ryu
Posts: 990
Joined: Sun Jun 10, 2012 8:03 am
Location: Casper

Re: Good Deal on Drill Bits!

Post by KJ Ryu » Tue Dec 17, 2019 1:40 am

Also, keep your grinding wheels dressed and flat.

Image
Ron

2005 KJ, Hit-n-Run, 2am 6-17-2012, Totaled. :mad:
1977 SJ J10, 4v360, T18, D20, 37x14s, SOA & SF on tons, still ugly.
1978 SJ Wagoneer, 4v360, QT, 33x12.5s, lift by Sawzall :-bd NOT Running :(
1977 SJ J10, SniperEFI 401, QT, D44s, 31X10.5s :fsj:
2006 KJ
Mars wrote:One man's trans leak is another's penetrating oil :D


itselliott
Posts: 112
Joined: Sun Jun 10, 2012 1:58 pm
Location: VVest Michigan

Re: Good Deal on Drill Bits!

Post by itselliott » Thu Dec 26, 2019 8:05 am

RJ Kyu……..
Exactly correct on both counts! :-bd


threepiece
Posts: 122
Joined: Mon Apr 20, 2020 8:33 am

Re: Good Deal on Drill Bits!

Post by threepiece » Tue Apr 21, 2020 8:18 pm

i have an easy to remember guide to help those who are unsure what spindle speed (rpm) to use for a particular size drill. I call it the “5 rule” and it works good for most drilling through mild steel. For a starting point or baseline I use a 1/2” drill which is .5” spinning at 500 RPM (notice the two fives). From there if you double the size of the drill you can divide the speed in half to 250 RPM. Again from the baseline of .5”, if you divide the diameter in half to a 1/4” drill you could double the speed to 1000 RPM.

Using this simple system one could extrapolate spindle speeds for most sizes of drills in mild steel. Of course this only helps if you have speed indication on the power tool you are using. Softer materials like aluminum can be run a bit faster.
I used to name my FSJ’s after their previous owners, I realized I had too many when I had five named Rick.


SJTD
Posts: 1336
Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: Good Deal on Drill Bits!

Post by SJTD » Tue Apr 21, 2020 9:52 pm

I was taught (4 x the cutting speed)/diameter. Drill, mill, lathe, doesn't matter. Cutting speed for mild steel is 90, aluminum is 400. That's all I remember or routinely use. Values for other materials can be looked up.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.

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